This flowering vine is native to tropical South America, from Mexico to Brazil. In Costa Rica, it can be found growing from sea level to 900 m in elevation. Interestingly, it is not related to the common edible onion or garlic at all!
In its native habitat, it is said that the garlic vine attaches itself around the trunk of a large tree for support as it climbs skywards to reach for sunlight. The best location for the garlic vine is all-day full sun.
The terminal leaflet of this plant is often modified into a tendril that helps the vine to cling onto a support.
Because of its large size, it is only practical to grow the garlic vine in outdoor gardens with a trellis. It is a vine with a moderate growth rate and one need not worry that is will become an unruly resident in the garden.
Watering and Fertilizing the Garlic or Amethyst Vine
The garlic vine likes moderate watering and a rich well drained organic soil. Watering should be regular and thorough. During the hot dry season, it can take twice a day watering. In some literature I found on the internet, other gardeners mist the leaves of the plant in the morning during hot dry spells.
Although the garlic vine can survive without additional soil amendments, it will benefit from organic fertilizers especially in its growing phase until it is time for it to flower. For this purpose, I've used homemade fish emulsion fertilizer regularly with much success.
Pruning the Garlic Vine (Mansoa alliacea)
This vine grows moderately fast. So prune heavily after flowering. Shown below are the spent blooms of the garlic vine flower cluster.
Flowering period ranges anywhere between August to October. I prune it roughly above the nodes of the major branches only and leaving some leaves. A stable and mature vine will take this heavy pruning with no problems.
If in doubt, you can prune the vine in two stages to minimize shock. First, prune the top one-third of the plant, retaining the bottom two-thirds. The bottom two-thirds would have sufficient foliage to keep the vine alive and healthy. After a week, remove another one-third. Only a third of the original plant now remains. Be sure to retain some leaves on the old branches and a few young branches with leaves.
Propagation of the Garlic Vine (Mansoa alliacea)
So what do you do with the cut branches? You can throw them away or make cuttings out of them. Propagating the garlic vine is ridiculously easy, at least in a tropical country. The best time to plant stem cuttings is during the rainy season.
I usually just leave two nodes to a semi-hardwood stem that is about quarter-inch thick. Keep a pair of leaves on the top node. Put it into a mixture of sand and compost to start the rooting process. Rooting hormone powder is usually not needed. Rooting usually occurs in a couple of weeks and you should be ready to repot the rooted cuttings in about a month.
Air-layering or marcotting is another propagation technique where the Garlic vine responds well.
Flowering of the Garlic Vine or Ajos Sacha
Growing the garlic vine is one thing, but getting it to flower is an entirely different story. Once rooted, the seedling has no problem thriving and grows rather quickly even in the shade. But flowers? Not too easy.
The garlic vine likes and needs full sun for it to flower. I found this out when looking for the best location for the garlic vine (Mansoa alliacea). I've relocated the plant twice in three different location around the garden.
The garlic vine would flower best in an open fence or garden trellis that gets 8 to 10 hours of sunlight a day.
Two Distinct Looks of the Garlic Vine Flowers
This is the early stage when some of the flower buds have just bloomed.
It is at this stage when the different shades of purple may be seen on the flowers.
And then a latter stage when all the blooms are at their fullest. Here, most of the flower colors have faded to a pale lilac. At this stage, the older flowers begin to wilt and will shed in a few more days.
If you're thinking of hard pruning branches after the flowering, you may want to reconsider. I've discovered that there can be waves of flowering in the garlic vine. Those same branches that just flowered are capable of sprouting new flower buds again on the same nodes after a few weeks.